Reliability Analysis using Advanced Modeling Technique for MEMS Microphone

This paper presents a comprehensive failure analysis on a MEMS microphone and an innovative design approach to improve reliability performance. Finite element simulation and lumped parameter circuit modeling approaches are used to validate physical testing. We identify the critical back cavity volume and front volume etched cavity surface imperfections which primarily govern the failure mechanism. Strong dependence of the back cavity volume on the microphone reliability has been discovered for a given diaphragm thickness. The failure mechanism observed is the shattering of the diaphragm with the back-plate structure still intact. With the novel X-rib front volume etched cavity design, we succeeded in improving the reliability performance by more than 50% of the failure pressure, with the diaphragm and the back plate structure still remaining robust.